Comparative analysis of the volatile flavor compounds of Monascus-fermented cheese with different ripening periods by SPME-GC-MS, SPME-GC×GC-MS, and HS-GC-IMS

Monascus-fermented cheese (MC) has earned significant attention in recent years as an innovative dairy product. This study employed SPME-GC-MS, SPME-GC × GC-MS, and HS-GC-IMS to investigate the volatile flavor compounds of MC at four different stages of ripening (MC0d, MC30d, MC60d, and MC90d) to compare the unique attributes of these approaches. A total of 126 compounds were identified in this study, among which SPME-GC × GC-MS detected the highest number of volatile flavor compounds, with 94 compounds detected. A total of 82 volatile flavor compounds were identified by SPME-GC-MS and 34 by HS-GC-IMS. All those methods identified 18 compounds, among which isoamyl acetate, isobutyl butyrate, and isoamyl butyrate were identified for the first time. Partial least squares discrimination analysis (PLS-DA) indicated that all approaches could distinguish the volatile flavor compounds across the MC ripening periods, while HS-GC-IMS exhibited the highest efficacy in differentiating the cheeses. The results indicate that those analytical approaches are mutually beneficial in examining the MC aroma during ripening. Therefore, these methods can be selected and combined according to specific research needs and objectives.